1. Field of the Invention
The present invention relates to an exposure control device which is adapted for use with or in a photographic enlarger or printing device and which controls the exposure of photographic printing. The exposure control device of the present invention is, in particular, useful for printing wherein shading and/or burning-in is required.
2. Description of the Prior Art
In a shading or burning-in process during photographic printing, the ratio of the exposure for the portion to be shaded or burned-in to the exposure for the remaining portion of the picture is determined in accordance with the result of test printings. The actual time of exposure for each portion is calculated based on this ratio. Already available to photographers is a photographic enlarger with a timer that visually displays the exposure time elapsed during the printing process or visually displays the time left until the longest of the exposure times assigned to all the portions of the printing paper expires. With such an enlarger, the user must calculate, from the longest exposure time and the ratio of exposures, the exposure time necessary for the shading or burning-in and execute the shading or burning-in while remembering the calculated exposure time. Simultaneously, the user must measure the time by comparing the displayed elapsed time with the memorized exposure time.
However, in such an enlarger, not only the longest exposure time but also the calculated exposure time must be changed when the diaphragm aperture of the enlarging lens and/or enlarging magnification are changed. Thus, the available device requires complex operations such that the user has to calculate and memorize the exposure time for the shading or burning-in and execute the printing operation every time any enlarging conditions, such as the diaphragm aperture, enlarging magnification, the ratio of exposures, and so on are changed.